An aged oil water-based drilling fluid lubricant and a method of making the same

Abstract

The present application relates to the technical fields of drilling fluid lubricant, in particular to an aged oil water-based drilling fluid lubricant and a preparation method thereof. The aged oil water-based drilling fluid lubricant is prepared by mixing 2-5 parts of aged oil, 1-3 parts of polyhydroxy alcohol, 1-2 parts of alkylphenol polyoxyethylene ether, 0.1-0.2 parts of sodium dodecyl benzene sulfonate and 0.05-0.1 parts of sodium carboxymethyl cellulose. The present application uses aged oil to produce water-based drilling fluid lubricant, which can avoid the problems of aged oil demulsification, dehydration, mud and sand removal, realize the resource utilization of aged oil, and reduce the generation amount of hazardous waste; the use of polyhydroxy alcohol and its cloud point characteristics realizes the wrapping and deblocking of aged oil, can control the deblocking conditions, and realizes the fixed-point lubrication of the selected well wall rock. The lubricity of aged oil can be fully utilized, the utilization rate of aged oil is improved, and the lubrication effect is improved.

Description

Technical Field

[0001] This invention relates to the field of drilling fluid lubricant technology, and in particular to an aged oil-water based drilling fluid lubricant and its preparation method. Background Technology

[0002] Aged oil is a byproduct of oilfield production, primarily originating from the emulsion zone of settling tanks, spilled oil, well workover wastewater, fracturing flowback fluid, and equipment backflushing. This oily waste, along with the oily sludge from the bottom of the settling tanks, is discharged into the station's waste liquid pond. In the waste liquid pond, it settles and separates, undergoing complex physicochemical reactions due to prolonged exposure to environmental factors such as air, temperature, and sunlight, as well as the mixing of various emulsifiers and dust. This process continuously aggregates at the oil-water interface, forming a highly stable emulsion, commonly known as aged oil. Aged oil production is substantial in various oilfields, especially in tertiary oil recovery areas, where the extensive use of polymer flooding agents significantly increases its production. For example, the Fengcheng operating area of ​​Xinjiang Oilfield produces over 20,000 tons of aged oil annually, the Jiqing operating area produces approximately 10,000 tons annually, and the No. 1 Oil Production Plant produces 10,000 to 15,000 tons annually. Due to its crude oil content and economic value, aged oil is typically recycled back into the crude oil dehydration and separation system for further processing to extract the remaining crude oil.

[0003] However, due to the diverse formation mechanisms and complex composition of aged oil, its properties and morphology differ significantly from crude oil, making it difficult to successfully and economically process using crude oil treatment processes. Therefore, re-mixing aged oil into the crude oil treatment system can severely impact the system, frequently leading to dehydration failures. Furthermore, aged oil contains highly conductive solid particles such as iron, zinc, manganese, and FeS, which can cause frequent tripping of the electro-dehydrator during electro-dehydration, and even lead to accidents such as breakdown of the internal electrode plates and insulation devices. In addition, because aged oil treatment is unsuccessful, it can only be circulated within the crude oil dehydration system, undergoing repeated sedimentation and separation, increasing the energy consumption of the dehydration system and significantly reducing the crude oil treatment efficiency. Therefore, scholars both domestically and internationally have conducted extensive research and proposed methods such as electrochemical demulsification, centrifugal separation, thermochemical sedimentation, and resource utilization to treat aged oil separately. However, aged oil typically exists as a water-in-oil emulsion with high water content, complex composition, and high emulsion stability. Conventional demulsification and dehydration methods are difficult to implement effectively. Individual treatment requires high temperatures and chemical concentrations 2-3 times higher than conventional crude oil treatment, posing significant challenges and severely impacting normal oilfield production. Currently, due to cost and technological limitations, a considerable portion of aged oil cannot be effectively treated, resulting in substantial waste.

[0004] Water-based drilling fluid refers to the general term for various circulating fluids that meet the needs of drilling operations during oil and gas drilling. From the perspective of fluid media, water-based drilling fluid is drilling fluid with water as the continuous fluid medium. It is a multiphase dispersion system composed of bentonite, water (or brine), various treatment agents, weighting materials, and drill cuttings. Drilling fluid lubricants are mainly used to reduce the flow resistance and filter cake friction coefficient of drilling fluid, reduce drill bit torque, and increase its hydraulic horsepower to prevent sticking. Most drilling fluid lubricants are formulated from animal and vegetable oil derivatives, synthetic compounds (such as fatty phenolic amines), and surfactants. They mostly have excellent lubricity; these are liquid lubricants. Another type is solid lubricants, such as graphite glass microspheres, plastic microspheres, and carbon beads, specifically used to reduce drill pipe torque. Some lubricants have an anti-mud-packing effect on the drill bit and can also be called anti-mud-packing agents. The paper "Preparation and Performance Evaluation of an Emulsion-Type Drilling Fluid Lubricant" discloses the synthesis of plant oleamide using polyamine, cottonseed oil, and low carbonic acid as raw materials. The optimal synthesis conditions are: a molar ratio of polyamine, cottonseed oil, and low carbonic acid of 1:4:1, a reaction temperature of 168℃, and a reaction time of 2.5 h. Using the synthesized plant oleamide as the main raw material, sodium oleate is generated by neutralizing oleic acid with NaOH as an emulsifier, and silicone paste, kerosene, and CMC-HV are used as additives. An O / W emulsion-type drilling fluid lubricant was prepared experimentally with the following ratio: 8% (w) plant oleamide + 10% (w) oleic acid + 18% (w) kerosene + 2.5% (w) silicone paste + 7.14% (w) NaOH aqueous solution (mass fraction of 20%) + 0.1% (w) CMC-HV + water. Performance evaluation shows that this lubricant has superior lubrication properties. At a dosage of 0.5% (w), the lubrication coefficient of the drilling fluid decreases by ≥80%, without affecting the rheology and density of the drilling fluid. After aging at 170℃ in 15% (w) brine drilling fluid, the lubrication coefficient is below 0.10, indicating that the lubricant has good temperature and salt resistance. Although existing technologies can produce pure lubricants from vegetable oils and white oils, which can be added to water-based drilling fluids for lubrication, the produced lubricants dissolve in the water of the drilling fluid and cannot be promptly and completely adsorbed onto the well section requiring lubrication, resulting in poor lubrication performance.

[0005] Existing methods involve producing aged oil for drilling fluids from crude oil. This process requires demulsifying and refining the aged oil to remove impurities such as water, mud, and sand, resulting in oil with properties similar to crude oil. Then, through a series of chemical and physical reactions and purification processes using emulsifiers, stabilizers, and extreme pressure agents, the corresponding drilling fluid lubricant is obtained. However, this process of producing lubricant from aged oil is cumbersome, time-consuming, and costly. Therefore, how to provide a drilling fluid lubricant containing aged oil and its preparation method, and how to establish a rapid, simple, and low-cost method for the resource utilization of aged oil, has become a problem urgently needing to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide an aged oil-water based drilling fluid lubricant and its preparation method, so as to solve the problems existing in the prior art.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides an aged oil-based drilling fluid lubricant, prepared from raw materials comprising the following parts by weight: 2-5 parts aged oil, 1-3 parts polyhydroxy alcohol, 1-2 parts alkylphenol polyoxyethylene ether, 0.1-0.2 parts sodium dodecylbenzene sulfonate, and 0.05-0.1 parts sodium carboxymethyl cellulose.

[0009] Preferably, the water content of the aged oil is 30-70%.

[0010] Preferably, the polyhydroxy alcohol comprises polyethylene glycol, polypropylene glycol, ethylene oxide-propylene oxide copolymer, ethylene glycol, glycerol, or methyl glucoside.

[0011] Preferably, the molecular weight of the polyhydroxy alcohol is 1500 to 20000.

[0012] Preferably, the cloud point temperature of the polyhydroxy alcohol is 5-10°C lower than the formation temperature of the wellbore being lubricated.

[0013] This invention also provides a method for preparing an aged oil-water based drilling fluid lubricant, comprising the following steps:

[0014] Aged oil, polyhydroxy alcohol, alkylphenol polyoxyethylene ether, sodium dodecylbenzene sulfonate, and sodium carboxymethyl cellulose are mixed to obtain an aged oil water-based drilling fluid lubricant.

[0015] Preferably, under laboratory conditions, the mixing is performed by stirring at a speed of 4000-6000 r / min on a high-speed stirrer for 20-60 s, and then stirring at a speed of 1500-2000 r / min on a low-speed stirrer for 3-5 min.

[0016] Preferably, under on-site construction conditions, the mixing is carried out by shearing dispersion in a shear pump for 3 to 5 cycles.

[0017] This invention provides a water-based drilling fluid lubricant for aged oil and its preparation method. By directly adding polyhydroxy alcohols with different cloud points, alkylphenol polyoxyethylene ethers, sodium dodecylbenzene sulfonate, and sodium carboxymethyl cellulose as treatment agents to aged oil, a water-based drilling fluid lubricant is formed through stirring. The polyhydroxy alcohols encapsulate and disperse the aged oil into fine oil droplets, which are then dispersed in the drilling fluid. By controlling the cloud point temperature of the polyhydroxy alcohols, phase separation occurs in the aqueous phase of the water-based drilling fluid, causing the polyhydroxy alcohols to lose their properties, thus completing the desealing process and releasing the aged oil. This released oil adheres to the wellbore rock in the desired lubrication section, providing a lubricating effect. This achieves the goal of establishing a rapid, simple, and low-cost resource utilization method for aged oil, and also provides a means for the production of selective water-based lubricants.

[0018] One of the key aspects of this invention is the use of an encapsulating agent. The main reason is that aged oil is an oil phase, immiscible with water. If aged oil is directly added to water-based drilling fluid, it floats on the surface and cannot provide lubrication. Therefore, it is necessary to encapsulate the oil phase, dispersing it through shearing to form appropriately sized oil droplets that are evenly dispersed in the drilling fluid. Upon reaching the bottom of the well, the encapsulating agent must rupture, allowing the oil droplets to exist as the oil phase in the drilling fluid, aggregate, grow, and adhere to solid surfaces such as rocks, forming a lubricating oil film. The key to this process is the encapsulating agent, which must be able to encapsulate the oil droplets and disperse them evenly in water, and automatically demulsify under certain controlled conditions.

[0019] The second key point of this invention is the selection of polyhydroxy alcohols as encapsulating agents. Polyols are defined as alcohols containing two or more hydroxyl groups (-OH) in their molecules. Commonly used polyhydroxy alcohols in drilling fluids include polyethylene glycol, polypropylene glycol, ethylene oxide-propylene oxide copolymers, ethylene glycol, glycerol, and methyl glucoside. This invention primarily uses polyethylene glycol with varying degrees of polymerization. Other polyhydroxy alcohols also exhibit the same effect during implementation. Polyhydroxy alcohols are surfactants with hydrophilic groups (hydroxyl groups) and lipophilic groups (hydrocarbon groups). The lipophilic groups dissolve in crude oil, while the hydrophilic groups bind to water, thus encapsulating aged oil and dispersing it in water.

[0020] The third key point of this invention is utilizing the cloud point of polyhydroxy alcohols to control the unsealing of the encapsulating agent and release the aged oil. The cloud point characteristic is unique to polyhydroxy alcohols. The cloud point temperature (CMT) refers to the temperature at which polyhydroxy alcohols in a solution of a certain concentration begin to micellize due to changes in the temperature of the solution or environment. Above this critical temperature, micellization of the polyhydroxy alcohol increases, and it precipitates from the solution as colloidal particles, causing the solution to become cloudy, eventually leading to phase separation. The cloud point temperature is essentially the issue of where polyhydroxy alcohols (PHAs) are most likely to precipitate. Therefore, the cloud point temperature of PHAs can be used to control the unsealing of aging oil encapsulating agents. This invention proposes selecting the degree of polymerization (molecular weight) of the PHAs encapsulating agent based on the formation temperature of the well section to be lubricated. The cloud point temperature of the PHAs should be 5-10°C lower than the formation temperature of the well wall to be lubricated. This is because if the cloud point temperature is too low (more than 10°C lower than the formation temperature), the oil droplets encapsulating the aging oil will unseale due to phase separation before reaching the well wall to be lubricated. The aging oil will precipitate from the water-based drilling fluid, accumulate, and adhere to the nearby well wall, failing to achieve the purpose of lubricating the target well section. If the cloud point temperature is too high, or is comparable to the bottom layer temperature, the encapsulating agent will not unseale, and the aging oil will remain dispersed in the drilling fluid, circulating with the drilling fluid and failing to achieve the purpose of lubricating the target well section.

[0021] In order to stabilize aged oil with added coating agents in water-based drilling fluid and enable it to quickly adsorb onto the rock surface to form an oil film, other treatment agents need to be selected. The other treatment agents proposed in this invention include alkylphenol polyoxyethylene ether, sodium dodecylbenzene sulfonate, and sodium carboxymethyl cellulose. Alkylphenol polyoxyethylene ether and sodium dodecylbenzene sulfonate are wetting agents, which can ensure that the oil phase can be quickly adsorbed onto the rock of the target well section.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention utilizes aged oil to produce water-based drilling fluid lubricant, which avoids problems such as demulsification, dehydration, mud and sand removal from aged oil, realizes the resource utilization of aged oil, and reduces the amount of hazardous waste generated.

[0024] This invention utilizes polyhydroxy alcohols and their cloud point properties to achieve the encapsulation and unsealing of aged oil. The unsealing conditions can be controlled, enabling targeted lubrication of selectable wellbore rocks. This fully utilizes the lubricating properties of aged oil, increasing its utilization rate and improving lubrication effectiveness. Attached Figure Description

[0025] Figure 1 Photograph of the base mud cake prepared using the aged oil-water based drilling fluid lubricant prepared in Example 1 of this invention;

[0026] Figure 2Photograph of the base mud cake prepared using the aged oil-water based drilling fluid lubricant prepared in Example 2 of this invention;

[0027] Figure 3 Photograph of the mud cake prepared using the aged oil-water based drilling fluid lubricant prepared in Example 3 of this invention. Detailed Implementation

[0028] This invention provides an aged oil-based drilling fluid lubricant, prepared from raw materials comprising the following parts by weight: 2-5 parts aged oil, 1-3 parts polyhydroxy alcohol, 1-2 parts alkylphenol polyoxyethylene ether, 0.1-0.2 parts sodium dodecylbenzene sulfonate, and 0.05-0.1 parts sodium carboxymethyl cellulose.

[0029] In this invention, the aged oil content is 2 to 5 parts, preferably 2.5 to 4.5 parts, more preferably 2.8 to 4 parts, and even more preferably 3 parts. If the aged oil content is too low, the oil phase is too small and it will not achieve the corresponding effect; if the aged oil content is too high, the operating cost will increase.

[0030] In this invention, the water content of the aged oil is 30-70%, preferably 35-65%, more preferably 40-60%, and even more preferably 45-55%. If the water content is less than 30%, the amount of subsequent coating agent needs to be increased. If the water content is greater than 70%, the lubricating effect of the produced lubricating oil will not meet the requirements due to the low oil phase content.

[0031] In this invention, the aged oil is taken from the aged oil sample of the oil and gas processing station, and the water content of the aged oil and crude oil is determined in accordance with GB / T8929—2006 (Determination of Water Content in Crude Oil).

[0032] In this invention, if the moisture content of the extracted aged oil sample does not meet the requirements, it can be obtained by mixing samples with different moisture contents. The calculation formula is as follows:

[0033]

[0034] In the formula: v i —Volume of the i-th blended aged oil sample, mL;

[0035] φ i —Moisture content of the i-th blended aged oil sample;

[0036] φ—Moisture content of the aged oil sample after blending;

[0037] In order to obtain a uniform aged oil sample, the aged oil should be mixed and stirred on a stirring instrument at a stirring speed of 2000-3000 r / min, preferably 2200-2800 r / min, more preferably 2500-2600 r / min for 5-10 min, preferably 6-9 min, more preferably 7-8 min, and even more preferably 5 min.

[0038] In this invention, the polyhydroxy alcohol content is 1 to 3 parts, preferably 1.2 to 2.8 parts, more preferably 1.5 to 2.5 parts, and even more preferably 2 parts. If the polyhydroxy alcohol content is too low, it cannot completely coat the aged oil and will not achieve the corresponding effect; if the polyhydroxy alcohol content is too high, it will increase the operating cost.

[0039] In this invention, the molecular weight of the polyhydroxy alcohol is 1,500 to 20,000, preferably 2,000 to 18,000, more preferably 5,000 to 15,000, and even more preferably 8,000 to 10,000.

[0040] In this invention, the polyhydroxy alcohol comprises polyethylene glycol, polypropylene glycol, ethylene oxide-propylene oxide copolymer, ethylene glycol, glycerol, or methyl glucoside, preferably polyethylene glycol, polypropylene glycol, ethylene oxide-propylene oxide copolymer, ethylene glycol, or glycerol, more preferably polyethylene glycol, polypropylene glycol, ethylene oxide-propylene oxide copolymer, or ethylene glycol, and even more preferably polyethylene glycol.

[0041] In this invention, the cloud point temperature of the polyhydroxy alcohol is 5-10°C lower than the formation temperature of the wellbore being lubricated, preferably 6-9°C, and more preferably 7-8°C.

[0042] In this invention, polyethylene glycol can be calculated using the following formula for cloud point and fractional mass.

[0043] T = 4.1x 2 -30x-3.385y 3 +14.06y 2 -17.79y+f(m)

[0044]

[0045] In the formula: x is the chloride ion content in the water-based drilling fluid, mg / mL;

[0046] y represents the content of polyethylene glycol in the drilling fluid, in mg / mL;

[0047] m is the molecular weight of polyethylene glycol j;

[0048] For polyethylene glycol as a coating agent, the above formula can be used to calculate the fractional mass and select polyethylene glycol with a suitable degree of polymerization. For other polyols, their cloud point can be determined experimentally and a polyol with a suitable cloud point can be selected.

[0049] The specific experimental method is as follows: A stoppered graduated cylinder containing a polymer alcohol solution is heated in a water bath heater. When the turbidity point is reached, the solution in the stoppered graduated cylinder becomes turbid. At this time, the regular script characters on the back paper can be seen clearly through the solution in the stoppered graduated cylinder. When the solution is not clearly visible, the solution is turbid. According to this rule, the turbidity point of the solution is the temperature at which the solution in the stoppered graduated cylinder changes from clear to turbid during the heating process, and similarly, the temperature at which the solution changes from turbid to clear during the cooling process.

[0050] In this invention, the mass fractions of alkylphenol polyoxyethylene ether, sodium dodecylbenzenesulfonate, and sodium carboxymethyl cellulose added to the drilling fluid are 1-2 parts, 0.1-0.2 parts, and 0.05-0.1 parts, respectively. If the content is too low, it will not have the corresponding effect; if the content of polyhydroxy alcohol is too high, it will increase the operating cost.

[0051] In this invention, the alkylphenol polyoxyethylene ether is 1 to 2 parts, preferably 1.2 to 1.9 parts, more preferably 1.3 to 1.8 parts, and even more preferably 1.5 to 1.6 parts.

[0052] In this invention, sodium dodecylbenzenesulfonate is 0.1 to 0.2 parts, preferably 0.11 to 0.18 parts, more preferably 0.12 to 0.16 parts, and even more preferably 0.14 to 0.15 parts.

[0053] In this invention, sodium carboxymethyl cellulose is used in an amount of 0.05 to 0.1 parts, preferably 0.06 to 0.09 parts, and more preferably 0.07 to 0.08 parts.

[0054] In this invention, the cloud point temperature of the aged oil-water based drilling fluid lubricant system is 86-114°C, preferably 90-110°C, more preferably 96-104°C, and even more preferably 100-102°C.

[0055] This invention also provides a method for preparing an aged oil-water based drilling fluid lubricant, comprising the following steps:

[0056] Aged oil, polyhydroxy alcohol, alkylphenol polyoxyethylene ether, sodium dodecylbenzene sulfonate, and sodium carboxymethyl cellulose are mixed to obtain an aged oil water-based drilling fluid lubricant.

[0057] In this invention, the mixing is performed on a high-speed stirrer at a speed of 4000-6000 r / min, preferably 4200-5800 r / min, more preferably 4400-5500 r / min, even more preferably 5000 r / min for 20-60 s, preferably 25-55 s, more preferably 30-50 s, and then on a low-speed stirrer at a speed of 1500-2000 r / min, preferably 1600-1900 r / min, more preferably 1700-1800 r / min for 3-5 min, preferably 3.5-4.5 min, more preferably 4 min.

[0058] In this invention, under on-site construction conditions, the mixing is carried out by shearing and dispersing in a shear pump for 3 to 5 cycles, preferably 4 cycles.

[0059] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0060] Example 1

[0061] Aged oil (45.5% water content) was taken from the Had crude oil processing tank of TLM oilfield. According to the method described above, 3 parts of aged oil, 2 parts of polyethylene glycol (molecular weight 14000), 1.5 parts of alkylphenol polyoxyethylene ether, 0.15 parts of sodium dodecylbenzene sulfonate, and 0.1 parts of sodium carboxymethyl cellulose were taken and stirred at 5000 r / min for 30s on a high-speed mixer, and then stirred at 1600 r / min for 3 minutes in a low-speed mixer to obtain aged oil water-based drilling fluid lubricant. The system turbidity point was 114℃.

[0062] The lubricant was added to the bentonite-based slurry at a ratio of 6.75 parts:100 parts to obtain a water-based drilling fluid slurry cake. Its performance was evaluated according to Chapter 6 of GB / T 16783.1-2014 "Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry - Part 1: Water-based Drilling Fluids" and QSY17088-2016 "Technical Specification for Liquid Lubricants for Drilling Fluids". The results are as follows:

[0063] Table 1 Performance test results of the aged oil-water based drilling fluid lubricant prepared in Example 1

[0064]

[0065] Figure 1 The image shows a photograph of the water-based drilling fluid-based mud cake prepared in Example 1. Using the lubricant produced by this invention, the adhesion coefficient of the drilling fluid-based mud cake was reduced by 67% and 63%, meeting the lubricant requirements (reduction of 50%).

[0066] Example 2

[0067] Take aged oil (45.5% water content) from the Had crude oil processing tank of TLM oilfield. According to the method described above, take 3 parts of aged oil, 1.5 parts of polyethylene glycol (molecular weight 9000), 1.5 parts of alkylphenol polyoxyethylene ether, 0.15 parts of sodium dodecylbenzene sulfonate, and 0.1 parts of sodium carboxymethyl cellulose. Shear and disperse the mixture for 5 cycles in a shear pump and mix to obtain a lubricant. The cloud point of the system is 86℃.

[0068] The lubricant was added to the field drilling fluid at a ratio of 6.25 parts:100 parts to obtain a water-based drilling fluid mud cake. Its performance was evaluated according to Chapter 6 of GB / T 16783.1-2014 "Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry - Part 1: Water-based Drilling Fluids" and QSY17088-2016 "Technical Specification for Liquid Lubricants for Drilling Fluids". The results are as follows:

[0069] Table 2 Performance test results of the aged oil-water based drilling fluid lubricant prepared in Example 2

[0070]

[0071] Figure 2 The image shows the water-based drilling fluid mud cake prepared in Example 2. Using the lubricant produced by this invention, the adhesion coefficient of the drilling fluid mud cake was reduced by 55% and 57%, meeting the lubricant requirements (reduction of 50%).

[0072] Example 3

[0073] Take aged oil (59.75% water content) from the Hongqian crude oil processing tank of XJ oilfield. According to the method described above, take 2.5 parts of aged oil, 2 parts of polyethylene glycol (molecular weight 12000), 1.5 parts of alkylphenol polyoxyethylene ether, 0.15 parts of sodium dodecylbenzenesulfonate, and 0.1 parts of sodium carboxymethyl cellulose. Shear and disperse the mixture for 5 cycles in a shear pump and mix to obtain a lubricant. The cloud point of the system is 102℃.

[0074] The lubricant was added to the bentonite-based drilling fluid at a ratio of 6.25 parts:100 parts to obtain a water-based drilling fluid mud cake. Its performance was evaluated according to Chapter 6 of GB / T 16783.1-2014 "Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry - Part 1: Water-based Drilling Fluids" and QSY17088-2016 "Technical Specification for Liquid Lubricants for Drilling Fluids". The results are as follows:

[0075] Table 3 Performance test table of aged oil-water based drilling fluid lubricant prepared in Example 3

[0076]

[0077] Figure 3The image shows a photograph of the water-based drilling fluid mud cake prepared in Example 3. Using the lubricant produced in this invention, the adhesion coefficient of the drilling fluid mud cake was reduced by 60% and 50%, respectively, meeting the lubricant requirements (reduction of 50%).

[0078] As can be seen from the above embodiments, the present invention provides an aged oil-based drilling fluid lubricant and its preparation method. The present invention utilizes aged oil to produce a water-based drilling fluid lubricant, which avoids problems such as demulsification, dehydration, mud and sand removal from aged oil, achieving resource utilization of aged oil and reducing the generation of hazardous waste. By utilizing polyhydroxy alcohols and their cloud point characteristics, the invention achieves the encapsulation and unsealing of aged oil, allowing control over the unsealing conditions and enabling targeted lubrication of selectable wellbore rocks. This fully utilizes the lubricating properties of aged oil, increasing its utilization rate and improving lubrication effectiveness.

[0079] Most existing technologies utilize vegetable oil / crude oil / waste oil / white oil / other oily substances + oleic acid + surfactants + macromolecular polymers, etc., under certain temperature conditions to formulate or synthesize drilling fluid lubricants. The difference in this invention lies in two aspects: First, it uses aged oil instead of other oils. Existing technologies require pure oil phases during production. Aged oil is a mixture, and processing it into pure crude oil requires high processing costs. This invention directly utilizes aged oil for lubricant production without processing, saving costs. Second, it uses polyhydroxy alcohol as an encapsulating agent. At a certain formation temperature, phase separation occurs, and the aged oil is released, giving the lubricant selectivity and controllability—a characteristic lacking in existing lubricants. Although there are existing technologies that directly use polyols to produce drilling fluid lubricants, these technologies differ significantly from this invention. Polyol drilling fluid lubricants utilize their inhibitory and plugging properties, while this invention utilizes polyols for encapsulation and decapsulation.

[0080] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An aged oil-water based drilling fluid lubricant, characterized in that, It is prepared from raw materials comprising the following parts by mass: 2-5 parts aged oil, 1-3 parts polyhydroxy alcohol, 1-2 parts alkylphenol polyoxyethylene ether, 0.1-0.2 parts sodium dodecylbenzene sulfonate, and 0.05-0.1 parts sodium carboxymethyl cellulose; The molecular weight of the polyhydroxy alcohol is 1500 to 20000; The cloud point temperature of the polyhydroxy alcohol is 5–10°C lower than the formation temperature of the wellbore it lubricates.

2. The aged oil-water based drilling fluid lubricant according to claim 1, characterized in that, The aged oil has a water content of 30-70%.

3. The aged oil-water based drilling fluid lubricant according to claim 2, characterized in that, The polyhydroxy alcohol includes polyethylene glycol, polypropylene glycol, and ethylene oxide-propylene oxide copolymer.

4. A method for preparing the aged oil-water based drilling fluid lubricant according to any one of claims 1 to 3, characterized in that, Includes the following steps: Aged oil, polyhydroxy alcohol, alkylphenol polyoxyethylene ether, sodium dodecylbenzene sulfonate, and sodium carboxymethyl cellulose are mixed to obtain an aged oil water-based drilling fluid lubricant.

5. The method for preparing an aged oil-water based drilling fluid lubricant according to claim 4, characterized in that, Under laboratory conditions, the mixing is performed by stirring at 4000–6000 r / min for 20–60 s on a high-speed stirrer, followed by stirring at 1500–2000 r / min for 3–5 min on a low-speed stirrer.

6. The method for preparing an aged oil-water based drilling fluid lubricant according to claim 5, characterized in that, Under on-site construction conditions, the mixing is carried out by shearing dispersion in a shear pump for 3 to 5 cycles.

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